UNIT 3 Sensation and Perception

EXAM WEIGHT: 6-8%

sensation

sensation

the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

Sens

perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

bottom-up processing

Starting with the sensory input, the brain attempts to understand/make sense.

Example: You see a long, slim, slithering creature on the ground… you process… ah! A snake!

top-down processing

Guided by experience and higher-level processes, we see what we expect to see.

Example: As an experienced hiker, you expect to see snakes on your hike so a stick, lizard, etc. all seem like snakes.

selective attention

the ability to focus on only one stimulus from among all sensory input

Inattentional blindness

failing to see visible objects when our attention is directed elsewhere

Example: while watching tv, you fail to notice someone walk in the room

Transduction

conversion of one form of energy into another

Psychophysics

the study of the relationship between the physical characteristics of stimuli

absolute thresholds

the minimum stimulation needed to detect a particular stimulus 50% of the time

difference thresholds

the minimum difference between two stimuli required for detection 50% of the time

signal detection theory

theory regarding how stimuli are detected under different conditions

subliminal

below one's absolute threshold for conscious awareness

priming

the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response

Weber's law

the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

perceptual set

a mental predisposition to perceive one thing and not another

context effects

describes how the context in which a stimulus occurs can contribute to how people perceive that stimulus

schema

a concept or framework that organizes and interprets information

extrasensory perception

the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition

parapsychology

the study of paranormal phenomena, including ESP and psychokinesis

color

An element of art that is derived from reflected light

wavelength

the distance from the peak of the next

amplitude

What is brightness/intensity of a color or the loudness of a sound influenced by?

Cornea

is the eye’s clear, protective outer layer covering the pupil and iris. Light enters the eye first through the cornea.

hue

the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth

intensity

the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude

pupil

the adjustable opening in the center of the eye through which light enters

iris

Colored part of the eye

lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

Retina

rods

retinal receptors that detect black, white, and gray; work best at night

cones

retinal receptor cells concentrated near the center of the retina; detect color; work best in light

Optic Nerve

the nerve that carries neural impulses from the eye to the brain

bipolar cells

eye neurons that receive information from the retinal cells and distribute information to the ganglion cells

ganglion cells

In the retina, the specialized neurons that connect to the bipolar cells; the bundled axons of the ganglion cells form the optic nerve.

retina, bipolar cells, ganglion cells, optic nerve, thalamus, brain

What steps does a neural impulse go through when going through the retina?

fovea

the central focal point in the retina, around which the eye's cones cluster

optic nerve

the nerve that carries neural impulses from the eye to the brain

accomodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

feature detectors

parallel processing

the processing of many aspects of a problem simultaneously

Young-Hemholtz Trichromatic Theory

the theory that the retina contains three different color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color.

color blindness

a variety of disorders marked by inability to distinguish some or all colors

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

gestalt

an organized whole

figure-ground

the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).

grouping

the perceptual tendency to organize stimuli into coherent groups

proximity

nearness, closeness

continuity

we perceive smooth, continuous patterns rather than discontinuous ones

closure

we fill in gaps to create a complete, whole object

similarity

the tendency to perceive things that look similar to each other as being part of the same group

Depth perception

the ability to see objects in three dimensions although the images that strike the retina are two dimensions

Visual cliff

a lab device for testing depth perception in infants and young adults

common fate

the tendency to perceive objects that are moving together as belonging together

pragnanz

every stimulus is seen as simply as possible

binocular cues

depth cues, such as retinal disparity, that depend on the use of two eyes

retinal disparity

By comparing retinal images from the two eyes, the brain computes distance. The greater the difference between two objects, the closer the object.

Colour blindness

A genetic condition that prevents individuals from discriminating between certain colours due to the weakness in or lack of one of the cones

monocular cues

depth cues available to each eye separately

Phi phenomenon

an illusion of movement created when two or more adjacent lights blinks on and off in quick succession

Perceptual constancy

Perceiving objects as unchanging even as illumination and retinal image change.

Colour Constancy

perceiving familiar objects as having consist colours, even if changing illumination alters the wavelengths reflected by the object

Size constancy

Stable size perception amid changing size of the stimuli

interposition

if one object partially blocks our view of another, we perceive it as closer

linear perspective

A monocular cue for perceiving depth; the more parallel lines converge, the greater their perceived distance.

relative size

The more distant an object, the smaller its image will be on the retina.

• mono cue

relative height

a monocular cue for perceiving depth; objects higher in our field of vision are perceived as farther away

texture gradient

the tendency for textured surfaces to appear to become smaller and finer as distance from the viewer increases

Convergence

The inward angle of the eyes focusing on a near object (turning your eyes in to look at a close object)

Stroboscopic Movement

Our tendency to perceive motion in a series of slightly varied still images flashed in rapid

Sensory adaptation

the process of filtering out, or getting used to, certain sensory information that our brains deem to be irrelevant

Perceptual adaptation

the process in which we take in that sensory information and our minds “fill in the blanks” with memories.

familiar size

because we know how large familiar objects are, we can tell how far away they are by the size of their retinal images

aerial perspective

monocular cue to distance and depth based on the fact that more distant objects are likely to appear hazy and blurred.

shading

A color or pattern used to fill the background of a cell

motion parallax

a depth cue in which the relative movement of elements in a scene gives depth information when the observer moves relative to the scene

audition

sense of hearing

frequency

determines how high or low a pitch is

pitch

a tone's experienced highness or lowness; depends on frequency

outer ear

The part of the ear that collects sound waves; consists of the pinna, the ear canal, and the eardrum.

middle ear

the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window

Cochea

a coiled, bony, fluid-filled tube in the inner ear. Sound waves traveling through the cochlear fluid trigger nerve impulses.

inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

cochlear nerve

the branch of the auditory nerve that transmits auditory information from the cochlea to the brain

basilar membrane

a structure that runs the length of the cochlea in the inner ear and holds the auditory receptors, called hair cells.

auditory cortex

the area of the temporal lobe responsible for processing sound information

cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

Helmholtz's place theory

the theory that links the pitch we hear with the place where the cochlea membrane is stimulated

frequency theory

in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

volley principle

The theory holding that groups of auditory nerve fibers fire neural impulses in rapid succession, creating volleys of impulses.

gate-control theory

States that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain.

pressure, warmth, cold, and pain

What sensations make up our sense of touch?

Nociceptors

pain receptors

olfaction

sense of smell

kinesthesia

our movement sense- our system for sensing the position and movement of body arts

example: when you are riding a bicycle, receptors in your arms and legs send information to the brain about the position and movement of your limbs.

proprioception

our sense of body position